Construction Impacts and Mitigation

Construction impacts and mitigation

Being a good neighbor during construction

WSDOT and Graham recognize that people living or working along the frontline and traveling through a complex project are those most affected by the work. While some effects of SR 520 construction are unavoidable, we strive to minimize effects on neighbors as much as possible.

WSDOT and Graham are implementing the following measures for neighbors and those traveling through Montlake:

  • Contractor performance incentives to go above and beyond community, mobility, and environmental contract requirements.
  • Visual screening through the installation of fencing and planting of fast-growing trees.
  • Noise dampening through the installation of Acoustifence materials in the Shelby-Hamlin area.
  • Full-time Community Liaison/Ombudsman.
  • Dust control (e.g., site watering).
  • Minimized disruptions to neighborhood street access.
  • WSDOT drop-in information center office in Montlake where the public can learn about the project, ask questions, and discuss concerns directly with project staff.
  • 24-hour noise and vibration monitoring program.
  • 24-hour hotline: 206-775-8885.

Nighttime construction during SR 520 Montlake Project

Graham will perform nighttime work under a City of Seattle-approved Major Public Project Construction Noise Variance. The variance sets limits for nighttime construction noise for the duration of construction.

Nighttime hours when variance is applicable:

Weekdays: 10 p.m. to 7 a.m. | Weekends and holidays: 10 p.m. to 9 a.m.

How will nighttime noise restrictions be monitored and enforced?

How will nighttime noise restrictions be monitored and enforced?

  • Electronic noise meters will record noise levels 24 hours per day.
  • Weekly and annual noise monitoring reports will be provided to the Seattle Department of Construction and Inspections. These reports will also be made available to the public.
  • A WSDOT-assigned independent noise inspector will be on site during all nighttime work to report any violations or neighborhood complaints to the Seattle Department of Construction and Inspections. Residents can report noise complaints to a 24-hour hotline: 206-775-8885.
What will nighttime noise mitigation measures include?

What will nighttime noise mitigation measures include?

  • Strict noise restrictions on jackhammers and other impact equipment between 5 p.m. and 8 a.m.
  • Not allowing trucks to idle longer than a few minutes.
  • Prohibiting pure-tone backup warning devices after 10 p.m.
  • Requiring the use of radios for long-range communications.
  • Designating haul routes that can reduce noise impacts caused by trucks.
  • Controlling noise at the source by using less noisy equipment and/or muffling the equipment.

    Construction vibration

    Some residents in the Montlake and Madison Park neighborhoods may notice vibrations when crews perform certain work during Montlake Project construction.

    Vibration monitoring

    Vibration monitoring

    • Graham will install vibration monitors around Montlake and Madison Park. The vibration monitors will provide the design-build contractor and WSDOT with necessary data to track and monitor vibration levels.
    • Home inspections have been offered to frontline homeowners and are available to other neighbors upon request.
    Vibration-producing equipment and activities

    Vibration-producing equipment and activities

    • Vibratory and impact hammers used for pile installation and drilling shafts.
    • Hoe-rams and munchers used for structure removal.
    • Excavators used for digging and trenching.
    • Vibratory rollers used for paving.
    • Concrete and flatbed trucks.

    If you suspect property damage from construction vibration, please notify the project team by calling the 24-hour construction hotline: 206-775-8885.

    Closures and detours

    Closures will take place primarily at night and on weekends to minimize traffic impacts. They will be scheduled to avoid major regional events whenever possible.
    Closure sign near SR 520 Trail.

    Types of closures

    SR 520 and local street closures

    SR 520 and local street closures

    • Full closure (all lanes, both directions).
    • Single-direction only.
    • Lane closures (at least one lane remains open).
    Sidewalk and trail closures

    Sidewalk and trail closures

      • Intermittent closures as needed with detours provided.
      • The 24th Avenue East bridge will close to pedestrians and bicyclists during the Montlake Project and reopen as part of the new Montlake lid. Detour routes will be available along Montlake Boulevard East and off of East Lake Washington Boulevard on a temporary path under SR 520.
      • The Bill Dawson Trail connection is expected to be closed during portions of the Montlake Project.

    Types of detours

    Short-term detours

    Short-term detours

    • When the highway, local streets, sidewalks or bike paths need to be closed, the design-build contractor will provide safe, clearly signed detours so that cars, buses, bicyclists and pedestrians can safely get to their destinations.
    Long-term, temporary traffic shifts

    Long-term, temporary traffic shifts

    • These detours will be used to temporarily reroute cars, buses, bicyclists and pedestrians around active construction work areas.

    Keeping SR 520 traffic moving during construction

    As crews start removing the old west approach bridge to build the West Approach Bridge South, all SR 520 traffic will shift onto the new West Approach Bridge North structure. During this interim construction period, the West Approach Bridge North structure will carry eastbound and westbound highway traffic.

    Current configuration: Westbound traffic travels on new West Approach Bridge North, eastbound on lower bridge
    Map showing Montlake Project current configuration
    2019: Montlake Project construction begins, and all traffic shifts onto West Approach Bridge North (similar to prior construction staging in 2016)
    Map showing Montlake Project construction beginning stage
    2023 (approx): Montlake Project construction complete, with two general-purpose lanes and one transit/HOV lane in each direction
    Map showing Montlake Project construction complete

    Click images to magnify.


     Mainline construction area

     Old structure

     New structure

     SR 520 Trail

    hov lanes iconTransit/HOV lane

     Temporary on-ramp

     Current on-ramp

    ramp removal iconRemoved on-ramp

    Maintaining transit access during construction

    Montlake Project construction activities will cause traffic and transportation disruptions due to adjustments in existing roadways, temporary closures, detours, and changes to pedestrian and bicycle access through the area.

    Existing Montlake flyer stops to close June 22, 2019

    • To prioritize rider safety and reliable access to transit, WSDOT, King County Metro, Sound Transit and Seattle DOT have determined that it’s necessary to close the highway-level flyer stops in Montlake during construction.
    • Bus stops will remain open and operational on Montlake Boulevard and at the Montlake Triangle/U-Link area.
    • There are almost 30,000 transit trips per weekday and about 6,000 per weekend day in the SR 520 corridor. About 700 of these daily trips use the SR 520 freeway flyer stops – approximately 2% of the total SR 520 weekday transit ridership.
    Map showing transit stops in the Montlake area.

    Click image to magnify.

    Icon showing bus stops that are closed.Freeway flyer stops closed during construction

    Icon showing bus stops that are open.Bus stops open during construction

    Transit service upon completion of the Montlake Project

    When complete, the Montlake lid will include new:

    • Multimodal transportation hub.
    • Local and regional bus stops.
    • Direct-access transit/HOV ramps between Montlake and the Eastside.

    Rendering of the future Montlake lid hub.

    Rendering of the future Montlake lid hub.

    Click image to magnify.

    Regional transit service map in the SR 520 corridor vicinity.

    Regional transit service map in the SR 520 corridor vicinity.

    Click image to magnify.

    Staging areas and haul routes

    Our goal is to keep the majority of haul-route traffic on I-5 and SR 520. There will be times when Graham must use city streets as haul routes because primary routes are not available or feasible. In these cases, Graham may use City-identified truck routes. Graham will obtain appropriate approvals and permits from the City of Seattle, as needed, and follow City of Seattle legal limits on vehicle weight, height and width. Some equipment and materials will be transported by barge via area waterways.

    Map showing primary and potential construction haul routes.

    Click image to magnify.

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